The 90 Day Threshold
If a Terminal Server requests a Terminal Services CAL (TS CAL) from a license server that does not have any activated TS CALs, the license server will distribute a temporary TS CAL that is valid for 90 days. This is a change from Windows 2000. In Windows 2000, only activated license servers could distribute temporary TS CALs. In Windows 2003, non-activated license servers can also distribute TS CALs.
The 120 Day Threshold
If a Terminal Server cannot locate a license server, the Terminal Server will still allow client devices to connect and run sessions for 120 days. In this case, the Terminal Server does not provide a temporary TS CAL. (After all, only license servers can provide the CALs that Terminal Servers distribute to clients.) This limit was 90 days on Windows 2000-based Terminal Servers.